The present invention relates to a coupler apparatus, for example, a coupler apparatus for coupling hoses such as fire hoses or coupling a hose and a device such as a pump, or a coupler apparatus for coupling other members, and a method of manufacturing such coupler apparatus. More particularly, this invention relates to a coupler apparatus comprising a pair of main bodies having identical structures without distinction between male and female structures, and a method of manufacturing the same.
In a conventional coupler apparatus, for example, a conventional insertion-type coupler apparatus for fire hoses, a pair of coupler bodies to be coupled comprise distinctive male and female bodies. One of the coupler bodies is constructed as a male metal fitting member, and the other as a female metal fitting member. Male metal fitting members cannot be coupled to each other, nor can female metal fitting members be coupled to each other. For example, in case of fire fighting, where a plurality of fire hoses are extended and coupled, the fire hoses may be misarranged such that the male fitting members or female fitting members are opposed to each other. Such misarrangement should preferably be prevented in view of facility and exactness in fire fighting. In addition, in the case of the conventional coupler apparatus, two types of metal fitting members with different structures, i.e. a male metal fitting member and a female metal fitting member, have to be manufactured, and this increases the manufacturing cost.
In order to overcome such drawbacks, there is a demand for an insertion-type coupler apparatus which comprises a pair of complementary coupler bodies with no distinction between male and female and with identical structures, wherein the coupler bodies can be freely coupled with no distinction between male and female, can be easily coupled/decoupled, have simple structures and high reliability, and can be manufactured at low cost.
Such a coupler apparatus, an apparatus can be thought of, wherein engaging projections and engaging recesses are mutually engaged in the axial direction and engaging hook portions provided on side faces of the engaging projections and engaging recesses are engaged in the circumferential direction, whereby a pair of coupler bodies are coupled. Various kinds of geometrical shapes can be considered as shapes of engaging portions of the coupler apparatus with such structure. In an actual coupler apparatus, however, smoothness of coupling, reliability, etc. need to be taken into account, and the following problems, for example, need to be considered.
A first problem is tightness in contact between, and machining of, the aforementioned complementary engaging projections and recesses.
In this type of coupler apparatus, the engaging projection and engaging recess are engaged. Thus, the smoothness in coupling/decoupling, and reliability, strength, etc. in coupling are greatly affected by the precision of the engaging projection, engaging recess and engaging portion. These elements are precisely machined by cutting. Specifically, cylindrical works for forming the coupling bodies are first manufactured, and then end portions thereof are milled. Thus, the engaging projection and engaging recess are formed.
Since these engaging projections and engaging recess have complementary shapes, the engaging recesses are cut at predetermined intervals and thus those portions intervening among the engaging recesses are formed as engaging projections. Where the engaging projections and engaging recesses are milled, one engaging recess is cut in the work, the work is then rotated by a predetermined angle, and a next engaging recess is cut. In this way, all engaging projections and engaging recesses are formed.
For example, where the number of engaging projections and the number of engaging recesses are six, respectively, these engaging recesses are formed at intervals of 60xc2x0. In addition, since these engaging projections and engaging recesses are substantially complementary, as mentioned above, the engaging projection and engaging recess are formed over about 30xc2x0.
In a general milling machine, a work is fixed and a milling tool is moved in one or two axes along a predetermined locus. The work is thus cut into a predetermined shape. In the case of the cutting by the milling machine, the cut faces of the respective parts are normally parallel to one another. Accordingly, for example, both inner faces of one engaging recess are parallel to each other, and also both side faces of an engaging projection formed between the engaging recesses are parallel to each other. Consequently, for example, if one inner side face or side face formed on the aforementioned engaging hook portion is a radial face passing through a central axis of the cylindrical coupler body, the other inner side face or side face is inclined at about 30xc2x0 to the radial direction.
As a result, where the coupler bodies are to be abutted on and engaged with each other, the other side face of the engaging projection of one of the coupler bodies and the other inner side face of the engaging recess of the other coupler body are displaced by 30xc2x0 from each other in opposite directions in respect of the radial face extending through the central axis. Consequently, a large gap is created between these side face and inner side face.
If such a gap is created, sand or pebbles enter the gap and cause malfunction of the coupler. Moreover, if the side face and the inner side face are engaged with an angle in the radial direction, a radial component force will occur in a reaction force acting therebetween. Besides, where the other side face or inner side face, for example, is provided with an urging mechanism, etc. for urging and engaging the aforementioned engaging hook portions in the circumferential direction, circumferential and radial component force will occur in the urging force of the urging mechanism.
According to various test results, it has turned out that drawbacks, such as loss of smoothness of coupling/decoupling of the coupler apparatus, occur due to the component force. Specifically, where the coupler bodies are to be coupled, the engaging projections and engaging recesses of the paired coupler bodies are axially engaged against the urging force of the urging mechanism until the engaging hook portions are completely engaged. In this case, if the radial component force is non-uniform among the engaging projections or engaging recesses, an undesirable radial repulsive force will occur in these coupler bodies. Consequently, the center axes of the paired coupler bodies are misaligned or inclined. Such drawbacks will deteriorate smoothness of coupling/decoupling.
In order to overcome the drawbacks, it is thought to incline said one side face or inner side face and the other side face or inner side face by equal angles in respect of the radial direction, e.g. 15xc2x0. However, where the internal pressure of the hoses is acting, a great axial load will act on said one side face or inner side face on which the engaging hook portion is provided. It is thus undesirable to inline the side face or inner side face in respect of the radial direction, on which such a load acts and the engaging hook portion is provided.
In order to facilitate mutual engagement of the engaging projection and engaging recess, it is desirable that the engaging projection and engaging recess be tapered such that the width thereof in the circumferential direction decreases toward the distal end or toward the bottom. In this case, however, the side face and inner side face of the engaging projection and engaging recess are also inclined in respect of the axial direction, and the directions of the aforementioned component force become more complex. A predetermined gap is provided for smooth engagement between the engaging projection and engaging recess. This gap may cause the central axes of the paired coupler bodies to be easily displaced or inclined during coupling. Consequently, the smoothness in engagement may be deteriorated due to the aforementioned undesirable component force. In particular, in the case of the coupler apparatus for fire hoses, the smoothness and exactness of coupling is important and the factors of deterioration in smooth coupling need to be eliminated.
A second problem relates to improvement of reliability in engagement of the engaging hook portions of the engaging projections.
In the coupler, jaw portions of the engaging hook portions are engaged and coupled in the circumferential direction. If an external load or shock acts to rotate the coupler bodies, the engagement of the engaging hook portions may undesirably be released. In particular, when no hydraulic pressure acts within the hoses, no axial load acts on the engagement portion between the engaging hook portions and the engagement tends to be undesirably released.
A third problem relates to removal of water from the inside of hoses at the time of storing the hoses, in a case where the coupler apparatus is applied to the coupler for hoses such as fire hoses.
In the prior art, when fire hoses, for example, are wound and stored after use, the coupler apparatuses provided between the fire hoses are decoupled and each fire hose is wound individually. However, where many fire hoses are connected over a long distance, it will require many persons and labor to wind and store each fire hose individually, and this is inefficient.
To overcome this problem, it is thought to automatically wind many fire hoses which are connected and extended over a long distance. For this purpose, a system may be used wherein, for example, a self-advancing vehicle is provided with a large-sized winding reel and the extended fire hoses are automatically wound by the winding reel.
Where this apparatus is used, however, if coupler apparatuses of many connected fire hoses are first separated, it becomes necessary to attach the end portion of each fire hose at the time of winding, and the efficiency of work decreases. To overcome this problem, it is preferable to wind up many connected fire hoses without separating them.
In this case, however, removal of water from the inside of the connected fire hoses is difficult. When fire hoses are wound up, each hose is flattened in cross section. It is thus necessary to exhaust water from the hoses. Where the couplers of the fire hoses are first separated, as mentioned above, water is easily exhausted from ends of fire hoses. However, where may fire hoses in the connected state are to be wound, water remaining in the hoses is not easily removed. Consequently, the speed of winding decreases and the resistance to winding increases. In particular, where fire hoses are extended over an ascending slope, internal water is difficult to exhaust due to water head and the above problems become more conspicuous.
On dredging sites, civil work sites or construction sites, many water-feed hoses are often connected over a long distance for exhausting or supplying water. Such water-feed hoses have large diameters and high rigidity and their cross sections are not easily reduced. In a state in which the hoses are filled with water, the hoses are heavy and are difficult to handle. It is thus necessary to exhaust water from the water-feed hoses before separating couplers of the water-feed hoses and removing and storing the hoses.
However, where water-feed hoses are extended over a long distance on a place with a great difference in level, it may be difficult to completely exhaust water due to an internal negative pressure in the hoses, even if water is to be exhausted from one end of the connected water-feed hoses. In such a case, it is also difficult to separate couplers provided midway along the connected water-feed hoses. As a result, the work for removing and storing the water-feed hoses becomes very difficult.
The present invention has been made in consideration of the above circumstances. The object of the present invention is to provide a coupler apparatus comprising a pair of coupler bodies which have no distinction between male and female and have the same structure, and a method for achieving sure and smooth engagement in this coupler apparatus and manufacturing the coupler apparatus with high efficiency.
In order to achieve the object, a coupler apparatus of this invention comprises coupler bodies and each coupler body has complementary engaging projections and engaging recesses. One side face of each engaging projection has an engaging hook portion, and the engaging hook portions of the engaging projections are engaged with each other.
At least both side faces of the engaging projection or at least both inner side faces of the engaging recess are defined by substantially radially extending planes passing through or near a center axis of the coupler body.
As regards the engaging projections and engaging recesses with such shapes, since their both side faces or both inner side faces are defined by radially extending planes, both side faces or both inner side faces are tightly engaged in the radial direction when the paired coupler bodies are abutted upon and engaged with each other. Accordingly, the gap between the side faces can be reduced to a minimum necessary for engagement/disengagement of the coupler bodies, and entrance of sand, mud, etc. in the gap can be prevented.
Since the side faces are mutually opposed in the radial direction and disposed close to each other or put in tight contact, no component force occurs in an undesired direction at the time of engagement. Thus, the engagement is made smooth, easy and sure.
Preferably, in the coupler apparatus of the present invention, one side face of the engaging projection is provided with an engaging hook portion, and the other side face of the engaging projection is inclined with respect to an axial direction of the coupler body such that the other side face is reduced in width toward a distal end portion thereof. Accordingly, engagement between the engaging projection and engaging recess is made easy and ensured. In this case, too, since the inclined other side face is defined by the radially extending plane passing through the central axis, the other side faces are tightly engaged and the gap therebetween is reduced to a minimum. Moreover, no component force occurs in an undesired direction.
According to a preferred mode of the present invention, there is provided a lock mechanism for preventing undesired disengagement of the engaging hook portion.
The coupler apparatus of the present invention has optimal characteristics as a coupler apparatus for fire hoses, water feed hoses used in construction sites, dredging sites, etc., air hoses, hydraulic hoses, household water supply hoses, other hoses, pipes, etc. Where the coupler apparatus is used as a coupler for such hoses or pipes, abutment-type seal mechanisms are provided on front end faces of the coupler bodies, thereby to ensure sealing between abutment faces of the coupler bodies.
The seal mechanism may have a function of draining an inside fluid when an internal pressure is substantially equal to an external pressure. With this type of seal mechanism, inside water can automatically be drained where a plurality of fire hoses are wound up in the state in which they remain attached to the coupler apparatus. Thus, the winding is facilitated. Even where the coupler apparatus is used for other hoses, removal or shift of the hoses is facilitated.
A manufacturing method of the present invention comprises the steps of: holding a cylindrical work for forming at least part of the coupler body such that the work is rotatable about a central axis thereof; holding a milling tool for cutting an edge portion of the work and forming the engaging recesses and engaging projections such that the milling tool is movable in an axial direction of the work; and cutting the edge portion of the work while the work is being rotated about the central axis thereof and the milling tool is being axially moved, thus forming the engaging recesses and engaging projections.
According to this manufacturing method, all side faces or inner side faces of the engaging projections and engaging recesses are defined by radially extending planes passing through the central axis. According to this manufacturing method, even where the engaging projection or engaging recess has a simple shape such as a rectangular shape in plan, or a trapezoidal shape, a triangular shape or a curved shape in plan, the side faces can be defined by radially extending planes passing through the central axis.
The coupler apparatus of the present invention is applicable not only to the aforementioned hoses, pipes, etc. for fluid passage, but also to members through which no fluid is passed, such as structural members. In this case, as a matter of course, the aforementioned seal mechanism is not needed.
The coupler apparatus of the prevention may be formed of a metallic material, a synthetic resin material, or other freely chosen material. The manufacturing method is not limited to the above-mentioned cutting process, but a molding process, an injection molding process, or other freely chosen processes may be used.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.